1) Field of the Invention
The present disclosure relates to a method of file sharing, particularly a method to delete shared data which has been completely downloaded.
2) Description of the Prior Art
In the digital era for free flow of information, the digitalized information or data should be stored and further shared to users.
Among portable storage devices which are based on USB interfaces and have been popularized since 2000, the flash drives for fast and economic data storage facilitate data sharing. However, the personal security is undoubtedly at risk because the data stored in carriers such as flash drives is shared among users without restrictions and the deleted data is easily accessed via data recovery measures.
The popularization of Internet has made data storage evolve into online storage from existing flash drive-based storage. Moreover, the online storage for which the charge depends on physically occupied storage space has advantages such as neither requirement to purchase other physical storage devices nor data backup by users themselves.
The patents for online storage are summarized as follows:
Patent No. TW 101123690 disclosed a mechanism/method based on cloud computing for sharing of encrypted files and authority management. The mechanism/method features the asymmetric encryption algorithm (e.g., RSA TOKEN) which is used to further encrypt an encryption key during encryption of high sensitive data. Meanwhile, a recovery key governed by a server for hierarchical data control is also used to encrypt the encryption key for security of encrypted files stored in clouds, hierarchical access via the server for hierarchical data control, and sharing of encrypted data.
Patent No. TW 099125643 disclosed a method for cloud services of data sharing based on a specific peer-to-peer channel and a system thereof. The specific channel is constructed with two or more physical USB-based transmission and storage devices via an online pairing process. In addition to direct hardware pairing mechanisms, social network applications are available in one-to-one or one-to-many pairing settings for more intuitive and humanized file sharing. With online pairing completed, files can be directly accessed, transmitted or shared by users via online USB-based transmission and storage devices. Furthermore, users who login a social network are able to preview or subscribe online files or purchase services for authority of file transmission with virtual currency.
Patent No. TW 102117420 disclosed a cloud computing system which fully reduces storage space occupied by an application in a user's device. With the size of a minimizing set, an application resource file installed in an application has a placeholder which substitutes for remaining application resource files and is an empty file looking like an application resource file. A program installed in a user's device to capture an application resource file is capable of detecting any difference between an application resource file and an application resource file's placeholder when an application makes a request of an application resource file. With an application resource file's placeholder detected, a response error can be triggered by the program and an application resource file is acquired by a user device from a remote storage location in a cloud-based storage. Moreover, an application resource file's placeholder is used to replace an installed application resource file.
However, potential risks are threatening security of users who enjoy convenience of online storage, for example, the dilemma of exposing personal privacy or corporate secrets during fast data sharing and difficulty in flexibly controlling authority of a tree structure at management of shared resources.
Accordingly, a method of file sharing is presented to settle the above problems.